New mapper…

Street Fighter 2 Plus, or SF2+, extended mapper (or give it you’re own name!). The original SF2 mapper is mapped to four 512k rom segments (mapped into the upper 512k of the lower 1megabyte range). The first 512k of the 2.5megabyte image is fixed mapped to the lower 512k of the 1megabyte range. Writing any value to the $0000-$000f range, changes which upper 512k mapped into the lower 1megabyte address ranger. Of course this is mapped to $fff0-ffff since bank $00 is left at MPR7. The SF2 game only writes to $fff0-$fff3.

So the new mapper. It’s just an extension of the original SF2 mapper. But you have $fff0-ffff range. That’s up to 8.7megs or 69Mbits. And guess what? A private release of Mednafen WIP supports it. Yup, yup-yup-yup. I did some tests today on SF2 with the new mapper support today. Yay! Gonna do some SF2 stuff now. (I lost my though for a moment… oh yeah) Original bank of $00 for SF2 has some free space to add some hooks. Perfect!

4 Responses to “New mapper…”

Great site with lots of interesting technical informations. 🙂
I haven’t been able to find your email address, so I decided to post my message here.

Being a big fan of the PC Engine (especially RPGs such as Tengai Makyo, Startling Odyssey or The Legend of Xanadu), I had been wondering for some time if it would be possible to convert/port the Sega CD version of LUNAR The Silver Star and LUNAR Eternal Blue to the PC Engine.

I guess that LUNAR 2 would be too big or complicated as all the data (image and sound) is streamed. But I noticed that for LUNAR 1, when you remove all the audio tracks, the game’s iso file size is below 10 megs (US version) and around 25 megas (Japanese version).
Do you think it could be done ? By using the tiles/graphics or even upgrading the colors and reprogram an iso that would run on the PC Engine ?

I saw that you had successfully managed to emulate nes games such as dragon quest and castlevania on the pc engine, and also a version of Lords of Thunder running both on the Sega CD and the PC Engine. So I wanted to ask you about this.

I’m not a programmer at all, but I’m a professional storyboarder and animator. I also design characters and can do pixel art if necessary. So if you needed help in the art department, I’d be glad to help you. 🙂
When it comes to homebrew, I’ve been the cutscene director and character illustrator for the game Pier Solar (megadrive/megacd). This has nothing to do with graphics, but I’ve also done the french translation of Mysterious Song on the PCE.

“I guess that LUNAR 2 would be too big or complicated as all the data (image and sound) is streamed. But I noticed that for LUNAR 1, when you remove all the audio tracks, the game’s iso file size is below 10 megs (US version) and around 25 megas (Japanese version).”

If the destination is PC-Engine CD, then size isn’t really a problem. It has the same CD size limits. As for ram (specific areas/etc loaded at a time), that’s a different issue.
“Do you think it could be done ? By using the tiles/graphics or even upgrading the colors and reprogram an iso that would run on the PC Engine ?”

Using the assets of the original, most definitely. And yes, some things could be upgraded (like color for instance). The ISO itself is just a huge file. One huge file, with multiple pointers to data to audio (track #’s, relative addressing, absolute addressing, etc).

As for doing the game on the PC-Engine, the game engine itself would have to be written from the ground up. So no just translating the code on the fly, or running the original code like the NES projects I did. Not only is program code written specifically for SegaCD (one or both 68k processors), and won’t run on PC-Engine CD, the video hardware has some differences too (not only does things differently, but does some things PCE can’t). So a RPG engine written from scratch, that uses all the original assets of Lunar (or even upgraded assets; GFX, SFX, sound, cinemas, etc) would be the only way to get the game on the system.

“I saw that you had successfully managed to emulate nes games such as dragon quest and castlevania on the pc engine, and also a version of Lords of Thunder running both on the Sega CD and the PC Engine. So I wanted to ask you about this.”

Sorry for the confusion. The Lords of Thunder project contained both the SegaCD *and* the TurboCD versions of the game. I arranged it so that the specific system would load the correct version. I only hacked the TurboCD version so that it played the same CD track layout as the SegaCD version (SegaCD CD audio tracks had different numbers). Neither system can run each other’s program code.

But… if a game was made from scratch, it could be made to use the same assets on the CD, and be dual boot for both. Although, that’s not very optimal for either system. Just more of a neat concept.

Anyway, if you’ve worked with the Pier Solar team (and Frozen Utopia team), you’ll know that it’s a lot of work creating a game engine from the ground up. Well, in this case it would be replicating/simulating a game engine – so a bit less complex. It definitely takes a dedicated team. If that’s what you’re looking to put together, then I’d be happy to help out on the technical and coding side. Though, I’ll be honest with that I probably wouldn’t make a very good lead programmer. I’ve got the skill, but keeping motivation up to get such work done, isn’t my strong point (I tend to get the strong urge to work on other stuff. Hence why I jump from GFX, to sound, to music, to hacking, to game logic, etc. Like a big rotating table. It’s almost fresh and exciting).

I see. Thanks for your response.
Actually, it’s not my habit to lead a group either, as I’m used to work alone, and I don’t really know other people who would be interested by this kind of project.
But I wanted to ask about these issues out of curiosity. So it could be done, if a specific game engine was programmed for the PC Engine, that could handle the original MegaCD graphic assets (which could be upgraded in the process.)
When it comes to the graphics upgrade, I know I could do it alone, but on the programming side, I don’t have any clue.

I could send you the game file, just in case. But I suppose you wouldn’t have the time or patience to work on this, right ? 🙂

Maybe I could find some people in the french PC Engine forums who could be interested by this. I’ll try to ask for help (programmers) there and shall contact you if I have something new in the future.
Thanks,